Plastics manufactured today for use in articles such as children's toys and products which are placed in the mouth of the user either by design or action of the user pose certain health risks to the user, i.e., toxicity to the user from the polymers used to manufacture the article or toxicity from the processing aids used in the manufacturing of the polymeric article. In addition to the direct health risks to the user of these articles, there may be environmental hazards as well.
Polyvinyl chloride (PVC) is a commonly used polymeric material for the manufacture of children's toys and products. Polyvinyl chloride is also used in a number of other articles such as toothbrushes, toys, eating utensils, food storage containers, and dinnerware. Since softness which is the ability of a compound to bend, yield or become flexible when gentle pressure is applied, (i.e., having a glass transition temperature from about 15° C. or higher) is not an inherent property of PVC as well as other plastics, and since softness is a desired component for many of the articles made from PVC or other plastics, especially articles intended to be used by children, there is a need to add this property to the PVC. A common way of addressing this need is to add or employ a processing aid in the manufacturing process. Processing aids generally are added in the manufacturing of polymeric materials to increase flexibility, workability and extrudablitiy of the end product. In the case of PVC, processing aids generally referred to as plasticizers and exemplified by a class of compounds known as phthalates are used to add softening and flexibility properties to the end product made from PVC. Phthalates are alkyl esters of isomeric benzenedicarboxylic acids. However, these compounds (phthalates) have been linked to liver and kidney damage. Also, it has been reported in the literature that when used as a processing aid in the preparation of products made of PVC, the phthalates can be leached out of the PVC product. This leaching occurs when the PVC product containing the phthalates comes in contact with human saliva. This situation is of particular concern with products that are intended for use by children, especially children under the age of three.
From an environmental standpoint, the PVCs currently on the market pose health and environmental hazards when the products are eventually destroyed or eliminated through combustion or thermal decomposition. When PVCs are burned, they decompose in to chlorinated chemicals, chlorine and hydrochloric acid, which are toxic. Chlorine and hydrochloric acid are corrosive and the chlorinated compounds are often flammable, as well as corrosive, and destructive to the protective stratosphere which is implicated in global warming and increased cancer hazards due to excessive UV exposure.
Plastics currently on the market, which add potentially toxic plasticizer additives, do not have low glass transition temperatures allowing for more flexibility and softness as desired when a user is handling, i.e., softening them from contact with the body caused by body heat. These plastics also do not offer abrasion resistance, durability, brilliant coloring and weather resistance in one product.
Therefore, there exists a need in the art for a polymeric material, free of toxic plasticizers, having softness, flexibility, abrasion resistance, durability, coloring and weather resistance properties, and useful in the manufacturing of products which may be placed in the mouth either by design or by the action of the user. A need especially exists for a polymeric material having the aforementioned properties for the manufacturing of products used by children, particularly children under three years of age.